Turkey declared three days of mourning following Saturday's nearly simultaneous explosions that targeted a peace rally attended by activists, labour unions and members of the pro-Kurdish Peoples' Democratic Party.

Mourners were held back by police who insisted investigators were still working at the site.

There was no immediate claim of responsibility for the attacks but Prime Minister Ahmet Davutoglu said Kurdish rebels and Islamic State militants were the most likely culprits.

Remzi Caliskan, Ankara representative of the Confederation of Progressive Trade Unions of Turkey said: "We will never forget. We will hold the responsible ones to account. We will never leave the responsible ones alone."